1. Field of the Invention
The present invention relates to a method for manufacturing an ink jet recording head for discharging an ink in an ink jet recording apparatus.
2. Related Background Art
The conventional manufacturing method (casting method) of a nozzle for this kind of ink jet recording head will be described. FIGS. 4A to 4F show illustrative sectional views (provided that, FIG. 4C is a plan view) of a conventional process. These figures show, respectively,
(a) a state after the molding of a positive resist,
(b) a state after the molding of a liquid chamber printing agent (a printing agent for patterning a liquid chamber),
(c) the plan view of a top plate,
(d) a state after the fixing of the top plate,
(e) a state after the injection of a casting material, and
(f) a state after cutting and removal for the formation of discharging orifices.
According to a conventional casting method, a positive photoresist (a pattern material) 2 for forming an ink flow path (hereinafter referred to as xe2x80x9ca nozzlexe2x80x9d sometimes) is applied onto a heater board substrate 1 which is a first substrate provided with an electro-thermal converting element (not shown) as a discharge pressure generating element, followed by exposure and development to form the pattern of the nozzle (FIG. 4A). Afterward, a pattern material (a printing material) 3 for a portion which will be an ink liquid chamber is formed by screen printing or the like so as to be higher than the height of the nozzle (FIG. 4B).
Next, a top plate 5, as a second substrate, made of a glass plate or the like and provided with an ink feed opening 6 and an injection opening 7 for feeding a casting resin 8 referred to hereinafter is fixed on the heater board substrate 1, the pattern material 3 for the ink liquid chamber being used as a spacer (FIGS. 4C and 4D), and the casting resin 8 which will become a nozzle wall is then injected through the injection opening 7 for the casting resin 8 (FIG. 4E).
Furthermore, in order to form a discharge orifice 10, the heater board substrate 1 provided with a heating resistor, the resist having a nozzle shape, the wall of the nozzle, the resin forming a ceiling, and the glass plate covering the upper surface are simultaneously cut by a dicer in a usual manner. Reference numeral 12 shows the center line of cutting.
Lastly, the resist forming the nozzle is removed with an etchant such as NaOH to form the nozzle (FIG. 4F). This method has some advantages. For example, the nozzle can be formed in the state of a high density, and the shape of the respective nozzles can be made uniform.
However, with regard to the position where the injection opening 7 is formed through the glass plate or the like in accordance with this manufacturing method, the following problem exits. That is to say, in order to inject the casting resin 8 without generating air bubbles on the portion of the nozzle wall, the resin 8 is preferably allowed to flow into the liquid chamber through the nozzle portion, and the injection opening 7 is located in the vicinity of the nozzle (this way, even if some air bubbles get into the wall portion of the liquid chamber, the performance does not deteriorate because of ink leakage).
For the installation of the injection opening 7, the following two positions can be contrived.
(1) The case where the injection opening 7 is formed in the top plate 5 above the discharge orifice 10.
In order to easily inject the resin 8, the width of the injection opening 7 is required to be at least about 1 mm, but if it is attempted to increase the number of the recording heads in the first substrate 1 to decrease the heads"", the injection opening 7 is excessively close to the ink feed opening 6, so that it is difficult from the viewpoint of strength to form the top plate 5, with the result that the manufacturing yield of the top plates 5 deteriorates.
In this connection, the distance from the face of the discharge orifice 10 to the liquid chamber is 0.5 mm or less, and in order not to lower the number of the recording heads, a cut width of 0.5 mm is necessary. In this case, however, the distance from the center line 12 of the cut portion to the hole of the ink feed opening 6 is at most about 1 mm, and hence it is substantially difficult to form the injection opening 7 within this distance.
(2) The case where the injection opening 7 is formed in the side of the nozzle portion at the side of the top plate 5.
In this case, if the resin 8 is injected through one side of the nozzle, it takes a long time from the start to the end of resin injection, due to the viscosity of the resin. Productivity becomes extremely reduced in the case of forming a full multiple recording head having many nozzles. If the resin 8 is injected through both the sides of the nozzle portion, the resin flowing from both sides meet at the central portion of the nozzle portion, and at this position, air bubbles are likely to be found.
The present invention has been accomplished with the intention of solving the problems of conventional manufacturing methods described above, and an object of the present invention is to provide an ink jet recording head having the improved stability of ink discharge and a high reliability for a long period of time. Another object of the present invention is to provide a method for manufacturing the ink jet recording head at a relatively low cost.
Thus, according to the present invention, there is provided a method for manufacturing an ink jet recording head comprising a discharging orifice for discharging an ink, a discharge pressure generating element for generating energy for ink discharge, and an ink flow path communicating with the discharging orifice, the method comprising:
a step of preparing a first substrate provided with the discharge pressure generating element,
a step of forming a removable pattern material for forming the ink flow path on the first substrate,
a step of preparing a second substrate provided with an ink feed opening for feeding the ink to the ink flow path,
a step of fixing the first substrate and the second substrate with the interposition of a predetermined space via the pattern material,
a step of injecting a resin for forming an ink flow path wall into a space between the first substrate and the second substrate,
a step of curing the resin,
a step of simultaneously cutting the first substrate, the second substrate and the cured resin to divide them into individual ink jet recording heads, and
a step of removing the pattern material to form the ink flow path,
wherein an injection opening is arranged in the vicinity of the portion for forming the ink flow path of the first substrate, and the resin is injected through the injection opening.
The employment of this method enables the achievement of the above-mentioned object.
With regard to the method for manufacturing the ink jet recording head according to the present invention, a through-opening for resin injection is preferably formed through the first substrate after the pattern material is formed on the first substrate.
With regard to the method for manufacturing the ink jet recording head according to the present invention, before the step of dividing the first and second substrates to form the individual recording heads, preferably a groove which does not go through the first substrate is formed from the back surface of the first substrate in a portion for the discharging orifice formable by the cutting, the pattern material is formed, the groove is bored through, and a resin injection opening is formed.
With regard to the method for manufacturing the ink jet recording head according to the present invention, in the step of cutting the first and second substrates to form the discharging orifice, it is preferable for a cut margin that is removed by cutting to be formed so that the width of the cut margin may be narrower than the width of the resin injection opening. This way, of the resin filled through the injection opening is exposed at the discharge orifice face.
With regard to the method for manufacturing the ink jet recording head according to the present invention, it is preferable that the pattern material is formed so as to project from a position to be cut for the formation of the discharging orifice, and the thus formed pattern material is exposed to the discharge orifice face by the cutting.
With regard to the method for manufacturing the ink jet recording head according to the present invention, it is preferable that the pattern material is formed so as to retract from a position to be cut for the formation of the discharging orifice, the thus formed pattern material is exposed to the discharge orifice face by the cutting, and afterward, the discharge orifice is formed by processing from the discharge orifice face.
As described above, according to the method for manufacturing the recording head regarding the present invention, the precision of the top plate can be improved and a time for resin injection can be shortened at a relatively low cost, which leads to the improvement of the yield of the recording head. Moreover, by selecting a suitable cutting tool, the choice of a substrate material and a resin material can be expanded, and in addition, a print quality can be improved.